In a standard rolling mill for making rod or wire (hereinafter referred to as wire) the wire/rod stock coming from the roll stands or prefinisher of the rod mill passes through a so-called wire block and thereafter through a calibrating block in which the final diameter and cross-sectional shape is imparted to the workpiece. Both the wire and calibrating blocks comprise a pair of roll stands spaced apart in the wire-travel direction. Thus the rolling of a workpiece to a finished wire is a three-stage process.
In the rolling mill or prefinisher, the wire rod block and the calibrating block, a plurality of roll stands are disposed, each of which has at least two interacting rolls, one above the other. The rolls are set at a defined spacing, resulting in the degree of workpiece deformation at the respective roll stand. The distance between two interacting rolls defines the roll gap or nip, which is crucial for the achieved degree of deformation.
It is known and common to adjust the rolls of the roll stands in the calibrating block specifically to such roll gaps that the wire has the desired final diameter after leaving the calibrating block. While the raw wire material is pre-rolled in the wire rod mill and in the wire rod block such that the diameter is rather close to the final dimension, precise calibration of the wire diameter only occurs in the calibrating block, to which end the rolls in the calibrating block are adjusted to the required roll gap.
The calibrating block therefore comprises control stages between the individual stands for adapting the reduction ratios to the defined fixed inlet diameter graduations from the wire rod block and/or from the rolling mill in the case of thick dimensions.
It is also known to provide two blocks with two roll stands each as the calibrating block, the stands being electrically adapted, if necessary, in order to be able to adjust the reduction ratios to fixed inlet diameter graduations as a function of the wire arriving from the wire rod block and/or—in the case of thick dimensions—from the rolling mill. Each block has a separate multimotor drive mechanism. The synchronization between the two blocks is performed electronically.
The disadvantage with this design is that it is very complex to properly configure the calibrating block since the rolls of the individual roll stands must be adapted to the individual roll gaps of the rolls in this block. This requires, for example, cost-intensive gear mechanisms on the calibrating block or electric synchronization.